330 EXPERIMENT STATION RECORD. [Vol. 41 



A. glabrum, XJlmus americana, and Quercua macrocarpa, showed the daily trans- 

 piration loss from the conifers during autumn to be nearly twice as great as 

 that from the deciduous species with the exception of Q. inacroctinpa. The re- 

 sults indicated tliat the conifers studied were more xerophytic than the broad- 

 leaved species during the summer, and that the needle habit was practically 

 as efficient as the deciduous habit in preventing serious loss of water during 

 winter. 



Light measurements, F. E. Clements (Carnegie Inst. Wasldngton Year Book, 

 17 (1917), p. 291). — A study of light intensity and quality on account of its 

 relation to plant requirements and behavior is said to indicate that the inten- 

 sity on heights such as Pike's Peak and Mount Garfield is scarcely or not at 

 all higher than at points 6,000 to 8,000 ft. lower. This is supposed to be due 

 to low humidity and the absence of dust and other impurities. Earlier obser- 

 vations have been confirmed that forest light is white light, containing the 

 various rays in essentially a normal proportion, although sufficient tests 

 have not been applied in such dense forests as those of cedar and hemlock on 

 the Pacific Coast and of beech in the East. 



Photosynthetic eflB.ciency, F. E. Clemekts and F. Long (Carnegie Inst. Wash- 

 ington Year Book, 17 (1918), p. 289). — Standard plants used as phytometers 

 have served to show the photosynthetic behavior of different species in 

 several habitats as well as the efficiency of each species in different habitats. 

 Studies have also been made of the photosynthetic activity of ecads growing 

 naturally in sun and shade and of paired species found in opposite light 

 conditions. An attempt has been made to determine the rate of carbohydrate 

 production during the day and its relation to the curve of daily light intensity. 

 Factor readings have been secured, special attention having been paid to light 

 intensity and quality. The method is expected to be valuable for use in forestry, 

 where reproduction and growth are largely determined by the light intensity, 

 also in permitting comparisons of the food-making efficiency of varieties of 

 crop plants, as well as of native species. 



Experimental pollination, F. E. Clements and F. Long (Carnegie Inst. 

 Washington Year Book, 17 (1918), pp. 293, 294). — ^A method of experimentation 

 designed to test the mutual responses of plants and insects is indicated, the 

 results of which up to the present time are said to have thrown much light 

 upon actual functions of flower parts, also to have furnished a large amount 

 of interesting material on the habits and individuality of insects. 



Field and g'arden study of genera and species, P. E. Clements and H. M. 

 Hall (Carnegie Inst. Washington Year Book, 17 (1918), p. 294)- — A general in- 

 vestigation of taxonomic criteria and study on the Madiete in field and garden 

 have been carried on for a number of years. The genera Chrysothamnus, 

 Artemisia, Atriples, and Haplopappus have recently been special subjects of 

 inquiry into criteria and their application to the problem of distinguishing 

 species from minor units. Field study of certain variants indicated has rendered 

 it possible to make a Vt'orking outline for the species and to relate the various 

 segregates provisionally to them. This constitutes the basis for the applica- 

 tion of statistical and experimental methods by which it is hoped to outline 

 a synthetic system based upon relationship. It should not only permit the 

 grouping of segregates of all sorts about the proper parent species, but should 

 likewise determine the nature of th(> minor unit, whether variant, ecad, or 

 mutant. At the same time it is proposed to furnish ft convenient and accurate 

 way of designating species and thoir minor imits. 



Variation and mutation in Epilobium, E. Clements (Carnegie Inst. Wash- 

 ington Year Book, 17 (1918), p. 293). — Studies continued for some years in con- 

 nection with E. spicatum produced in earlier work an unusual number of ap- 



